Background In addition to the persistence of SARS-CoV-2 infections, those with Influenza A/B and RSV have reappeared
in 2022/23. To compare the development of prevalence, clinical outcomes and risk factors, we analysed data
of the season 2023/24 from the same region/hospital as for 2022/23.
Methods Patients covering the whole age range with a positive polymerase chain reaction (PCR) test for SARS-CoV-2,
Influenza A/B, RSV were included from the internal, neurological and paediatric units of the RoMed hospital Rosenheim,
Germany/Bavaria, from August 1st 2023 to 29th February 2024.
Results Of 932 patients included, 912 showed single infections with SARS-CoV-2, Influenza A or RSV (47.9% female,
median age 68.0 years; 52.9% SARS-CoV-2, 23.2% Influenza A, 21.8% RSV). Co-infections (2.0%) and Influenza B (0.1%)
were negligible. In patients of age ≥ 18 years (n = 628, 68.5% SARS-CoV-2, 26.0% Influenza A, 5.6% RSV), patients
with Influenza A were younger compared to SARS-CoV-2 (p < 0.001), with RSV similar to SARS-CoV-2. Heart failure
and asthma were the most prevalent comorbidities for RSV, immunosuppression for Influenza A. Admission to Intensive
Care Unit (ICU) occurred in 111 patients (17.0% of SARS-CoV-2, 17.2% Influenza A, 28.6% RSV), and 59 patients
died (8.8% SARS-CoV-2, 8.6% Influenza A, 20.0% RSV). Low-flow oxygen supplementation and non-invasive ventilation
(NIV) were most frequent for RSV (68.6% and 20.0%, respectively), oxygen demand upon admission for Influenza
A (39.3%), without differences in high-flow oxygen supply or length of hospital stay. Among patients aged < 18 years
(n = 284, 21.4% SARS-CoV-2, 18.0% Influenza A, 57.1% RSV), 15 were admitted to ICU (4.8% SARS-CoV-2, 3.8% Influenza
A, 6.0% RSV); none of them died. Oxygen supply via high-flow, low-flow or upon admission was highest for RSV
(23.8%, 70.2%, 21.4%, respectively), as well as the length of hospital stay.
Conclusion Between 8/2023 to 2/2024, a large population of patients hospitalized due to respiratory tract infection,
showed relative contributions of SARS-CoV-2, Influenza A or RSV similar to those in 2022/23. The findings underline
that in both, adults and children, RSV posed a relatively higher clinical risk than Influenza A and SARS-CoV-2,
though absolute numbers remained highest for SARS-CoV-2.